But increased ethnic diversity could also have the effect of making white people more right-wing. Research by Harvard political scientist Ryan Enos suggests that when confronted with different racial groups, even liberal voters turn rightward. In one study, Enos sent pairs of native Spanish-speaking Latino men to ride commuter trains in Boston, surveyed their fellow riders' political views both before and after, and also surveyed riders on trains not used in the experiment as a control.
As America gets less white, inevitably more white citizens are going to come into regular contact with nonwhite citizens, which could lead to the kind of dynamics Enos describes on a mass scale. The problems don't arise as much when neighborhoods are well-integrated, but they're a major problem in cities and other areas that are racially diverse but geographically segregated — in other words, "in America." That's bad news for Democrats. "This difficulty is deeply structural and hard to overcome," Enos wrote me in an email. "As long as we live in a segregated, racially diverse society, a large portion of white voters will favor the party that does not include racial minorities."